1 SOURCE: Our World in Data and UN, 2020. 1 7 0 0 1 7 5 0 1 8 0 0 1 8 5 0 1 9 0 0 1 9 5 0 2 0 0 0 2 0 5 0 P r o j e c t i o n 2 1 0 0 P r o j e c t i o n 6 0 0 m i l l i o n 1 b i l l i o n ( 1 8 0 3 ) 2 b i l l i o n ( 1 9 2 8 ) 5 b i l l i o n ( 1 9 8 7 ) 7 . 7 b i l l i o n 2 . 1 % ( 1 9 6 8 ) 9 . 7 b i l l i o n 1 0 . 9 b i l l i o n 2 . 5 b i l l i o n 1 . 1 % 0 . 0 4 % ( g r ow t h b e t we e n 1 0 0 0 0 BC a n d AD 1 7 0 0 ) 2 0 2 0 1 . 6 b i l l i o n 6 b i l l i o n ( 1 9 9 9 ) The world 's population grew slowly until the 19th centur y. This is because there were high birth and death rates. In the 19th centur y, the population grew faster. Improvements in health care, hygiene and nutrition reduced the death rate. The population grew from around 1 billion (1,000,000,000) in 1800 to 1.6 billion (1,600,000,000) in 1900. In the 20th centur y, there was a population explosion. In the last four decades alone, the population grew from 3 billion (3,000,000,000) to 6 billion (6,000,000,000). In the 21st centur y, the population is growing at a slower rate once more. It is currently growing at 1 % per year, when in 1968, the highest growth rate in histor y was reached: 2.1 %. 5. Evolution of world population The influence of population structure Population structure tells us how a population is composed by age group and sex. The population structure of a territor y influences its fertility, birth and death rates. Therefore, population structure also influences demographic growth . According to age. The population is classified into three main groups: young people (aged 0 to 14), adults (aged 15 to 64) and elderly people (aged 65 and over). According to sex. The population is divided into males and females. Societies with a high percentage of young people and women of child-bearing age will have a high birth rate and high demographic growth . Populations with a low percentage of young people and women of child-bearing age will have a low birth rate and low demographic growth . Societies with a high percentage of elderly people will have a high death rate. If this is not compensated by the birth rate, the population will decrease. Continuous growth, but at different rates Over the last few centuries, world population has continued to grow. However, the growth rate has not remained constant. (5) On e b i l l i o n = 1 , 0 0 0 , 0 0 0 , 0 0 0 959143_02_p057_leyenda__billones_evol_pobl_mundial Define: birth rate, fertility rate. What is the relationship between these two indicators? List the data you would need to determine the population growth in a place. Explain how world population has changed over time. Think. What scientific, economic, social and other changes influence demographic growth? K E Y Q U E S T I O N S An n u a l wo r l d p o p u l a t i o n g r ow t h Numb e r o f i n h a b i t a n t s 31
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